Changing a lye:water ratio

[TashaBird]

Aka, can someone please help me with this math?! It’s so embarrassing how much trouble I have with this concept of lye ratio. And, just when I think I’ve finally got it, I get confused all over again. Here’s the story. I mixed up some %30 lye solution, but I forgot to add and dissolve my sugar first. So, I set that batch aside and started over, with the sugar. Now I’ve got this %30 solution that I would like to make into %50 solution. Let my accident force me to make the jump to trying MB lye solution! How much lye should I add to this to make it %50?
Thank you super much!!!
1075 water and 460g lye.

 

[DeeAnna]

You have 1075 g water and 460 g NaOH. You want to make a 50:50 solution. The total weight of dry NaOH has to be equal to the water weight in a 50:50 mixture. So --

Additional NaOH = 1075 - 460 = 615 g

 

[The_Phoenix]

Going by the recipe you included, you used 1,074 grams of liquid. To make this a 50/50% solution, or a 1:1 ratio of water:lye, your lye weight will need to also be 1,074 grams. Since you used 460 grams of lye already, subtract that from 1,074 to give you the remining lye you would need to add to the 30% solution. That gives you 614 grams of lye. So you need to add an additional 614 grams of lye.

Make sense?

 

[TashaBird]

Thank you SO much! It makes so much sense when you both write it out like that! Sometimes my brain just struggles with certain things, even though they seem obvious to others. I’m super grateful for your generous and kind responses! This group is just the best!!

 

[TashaBird]

Hi there. So, I added the 614g of lye to my solution to bring it up to %50. The previous %30 solution was cold when I added the extra lye and after adding that, it never got hotter than 105F. It seems as though the added extra lye never completely dissolved into the solution. It’s got a layer on top and looks sludgy. Any ideas what happened, and what I might do to save it?
I don’t think much water evaporated from the earlier solution because I put a loose cover on the container.

 

[TashaBird]

Should I maybe put the container into a tub of hot water and see if it will dissolve more?

 

[AliOop]

How cold is the solution? My MB lye solution gets quite a bit thicker at room temp, which for me is around 70-75 most of the year, and maybe 68 in the winter (because DH just wilts if the heater is blasting). Anyway, I wouldn't call it sludgy per se, but it is definitely thicker and pours more slowly than plain water.

Tell us more about this layer on top: is it white, or does it look like lint has settled on top? If so, that is pretty normal, too. It usually re-dissolves when I stir it up. If it is truly undissolved lye, that typically sinks to the bottom, IME, rather than floating to the top. Either way, you can heat up the lye solution a bit as suggested, and then stir it and see if it becomes more homogenized. You can also leave it alone and pour through a strainer when measuring it out. Your solution won't be perfectly 50:50, but your soap will turn out just fine.

ETA: although this probably doesn't apply at this time of year, MB lye solution should be stored above 65F to prevent the lye from precipitating out of solution.

 

[TashaBird]

How cold is the solution? My MB lye solution gets quite a bit thicker at room temp, which for me is around 70-75 most of the year, and maybe 68 in the winter (because DH just wilts if the heater is blasting). Anyway, I wouldn't call it sludgy per se, but it is definitely thicker and pours more slowly than plain water.

Tell us more about this layer on top: is it white, or does it look like lint has settled on top? If so, that is pretty normal, too. It usually re-dissolves when I stir it up. If it is truly undissolved lye, that typically sinks to the bottom, IME, rather than floating to the top. Either way, you can heat up the lye solution a bit as suggested, and then stir it and see if it becomes more homogenized. You can also leave it alone and pour through a strainer when measuring it out. Your solution won't be perfectly 50:50, but your soap will turn out just fine.

ETA: although this probably doesn't apply at this time of year, MB lye solution should be stored above 65F to prevent the lye from precipitating out of solution.

Thank you! I don’t know what “IME” is, but I think I get the gist.
I was making soap today, so I’ll mess with it in the next couple of days. I’ll post pics, if I can’t figure it out. Hopefully the heating and stirring will give me more confidence that it’s ok. I can’t afford to waste it! Maybe I won’t be MB lye after all then, because my soap area is regularly below 65F. Thanks again!

 

[AliOop]

You are welcome!

IME - in my experience
IMO - in my opinion
ICIM - in case it matters
IIRC - if I remember correctly

... and that's all I can remember correct ATM (at the moment).